1. Field of the Invention
The present invention relates, in general, to an apparatus for use in testing the retina for macular degeneration or the like.
2. Information Disclosure Statement
The macula is the portion of the retina of a person's eye which allows that person to see detail. Macular degeneration will cause a person's vision in the affected eye to become distorted, blurred, discolored, or otherwise abnormal. An Amsler grid is used by many people to test the vision in each eye, separately, for macular degeneration. The Amsler grid consists in general of a grid composed of a plurality of spaced apart horizontal and vertical lines forming a plurality of squares of the same size, and having a dot in the very center thereof. Typical instructions for using the Amsler grid are as follows:
A. Wear reading glasses if you normally use reading glasses. PA1 B. Cover one eye. PA1 C. Look at the center dot and keep your vision on it at all times. PA1 D. While looking directly at the center of the grid, and only at the center of the grid, be sure that all the lines are straight and all the squares are the same size. PA1 E. If you notice any area on the grid that becomes distorted, blurred, discolored, or otherwise abnormal, please call you doctor right away. PA1 F. Do this for each eye.
A modified version of the Amsler grid has been developed for use by patients especially after laser treatment for certain forms of macular degeneration. In this modified version, the center dot is replaced with a large "X" that extends from each corner of the grid and crosses at the very center thereof. The use of this modified Amsler grid is substantially the same as given above, except that the tester looks at the center portion of the "X" rather than at the center dot. It is important when using this modified Amsler grid that the tester keeps his or her vision on the center portion of the "X" at all times. However, since a patient after such laser treatment will always notice an area of abnormality on the Amsler grid, rather than making sure that all the lines are straight and all the squares are the same size, these patients, while looking directly at the center of the grid (i.e., at the center portion of the "X"), and only at the center of the grid, will make note of any change in the area of abnormality.
A problem many people with macula degeneration have with using an Amsler grid, especially those who have had laser treatment, is that sometimes the abnormality in that eye being tested is such that the center dot of the Amsler grid is distorted, blurred, or otherwise abnormal, making it difficult, if not impossible, for that person to look at the center dot and keep his or her vision on the center dot at all times during the test.
The prior art does not disclose or suggest the present invention. More specifically, nothing in the prior art, taken as a whole, discloses or suggests a retina tester including a grid having a grid pattern and having an aperture through the center of the grid pattern; and including illuminating means for illuminating the aperture through the center of the grid pattern of the grid.